* Now bootmnt/img_dev is always a ro-mount,
  and cowspace is first ro-mount then rw-mount.

* Fix a "hidden" bug: at the time of test [[ -ef ]], if devices nodes
  are not ready, such test will fail then archisodevice will mounted ro and
  when cow_device is mounted to be rw it fails.
  (I recently suffered this on a machine with slow USB)

Signed-off-by: Gerardo Exequiel Pozzi <vmlinuz386@yahoo.com.ar>